The present invention relates in general to apparatus for disengaging fish from gillnets, longlines, and similar fish capturing means as such means are hauled aboard fishing vessels so as to permit such freed fish to fall into the hold of the fishing vessel or into other suitable fish collecting and/or processing means; and, more particularly, to shaking apparatus for gillnets or the like having an elongate eye with a convexly shaped gillnet supporting surface and wherein the gillnet is passed over the convex surface as it is hauled aboard so that the rapid shaking movement of the apparatus serves to spread the gillnet over the convexly shaped surface and to impart non-uniform, relatively violent, shaking motion to that portion of the gillnet approaching and passing over the convex surface, whereby fish caught in the gillnet are shaken loose with those fish disposed beneath the gillnet being free to fall downwardly into the hold of the fishing vessel, while those fish disposed above the gillnet are shaken loose therefrom and, because of the generally convex configuration of the gillnet, tend to move towards and over the cork and lead lines on the outboard edges of the gillnet from where they are free to fall into the hold of the fishing vessel.
In the fishing industry, and especially in the commercial fishing industry, many different types of equipment are employed for catching fish. However, once caught and brought aboard the fishing vessel, it is necessary to disengage the fish from the fish capturing equipment--e.g., from purse seines, gillnets, longlines, and the like--so as to permit collection of the fish in the hold of the vessel for storage and/or processing. Where the fish are captured in, for example, a roundhaul seine or purse seine, they are not individually snared within the interstices of the net webbing but, rather, are collected in bulk within the confines of the net; and, consequently, the fish may be readily dumped into the hold by opening the purse over the hold. On the other hand, when fish capturing means are employed wherein the fish are individually snared by their gills in the net webbing, or by engagement with fish hooks on longlines or the like, the need to free the fish as they are hauled aboard presents significant problems. This is particularly true in the case of gillnets which are commonly on the order of two fathoms (12') in vertical height-- the span between the cork and lead lines--up to fifty fathoms (300') in length, although such gillnets do vary widely in size. For example, gillnets may vary from on the order of one fathom (6') to five fathoms (30'), or more, in vertical height; and/or a plurality of such nets may be strung together to form a single net up to and in excess of one thousand feet in length. Such nets are relatively heavy, cumbersome, and quite difficult to handle, even when not fully loaded with fish. These handling difficulties become even greater when the net is loaded with fish since catches are commonly from two or three tons per fifty fathoms of net length, or up to 200 lbs. of fish for every ten foot length of net.
When dealing with gillnets, as the net is hauled aboard with its catch of fish, it has generally been necessary for several fishermen to grasp the opposite edges of the net--viz., those edges including the cork and lead lines--and to manually shake the net in order to free the fish therefrom. This is a time consuming, labor-intensive job which requires considerable manpower and great strength and stamina. Moreover, the central portion of the gillnet tends to form a "pocket" as the net is physically shaken and, consequently, fish tend to collect in the center of the net rather than to fall off of the edges of the net into the hold. This has necessitated the use of "shaker strips"--viz., a strip running centrally along the length of the net where the mesh is sufficiently coarse that fish falling into the "pocket" can pass through the net webbing and drop into the hold. Such "shaker strips" are expensive to install and maintain; and, moreover, are ineffective for capturing fish when the net is in the water. That is, in a fishnet having a vertical height of twelve feet, if the "shaker strip" is two feet in width, then the effective capture area of the net is only ten feet per increment of length--i.e., an effective loss of approximately 16.67% of total net area. However, such a net is just as difficult to handle as one which is twelve feet in height but does not employ a "shaker strip".
Because of the considerable difficulties and significant physical labor involved when trying to disentangle fish from gillnets and the like, attempts have been made to mechanize the net shaking procedure. Generally, such attempts have involved highly complex mechanisms for beating and/or shaking the net as it is hauled aboard the vessel, normally with a "paddle wheel" type beater or with a mechanism for moving a generally horizontal net supporting surface up and down, with and/or without some component of motion along lines generally parallel to the direction of movement of the net as it is hauled aboard. Typical examples of such prior art attempts to solve the problem are those disclosed in Russian Pat. Nos. 185,624 (Oct. 22, 1966), 188,792 (Jan. 9, 1967), 199,557 (Aug.25, 1967), and 227,789 (Mar. 21, 1969). However, such attempts have not been commercially successful for a number of reasons. For example, when employing "paddle wheel" type beating mechanisms, the net shaker tends to rapidly damage the net. Moreover, the type of motions imparted to the net do not tend to move disengaged fish laterally towards the edges of the net but, rather, longitudinally along the length of the net. As a consequence, those fish freed from the upper surface of the net tend to collect in a "pocket" in the center of the net and this fact, coupled with the weight and flexible nature of the net itself, tends to prevent the fish collected on the upper surface of the net from falling into the hold of the vessel, thereby necessitating the use of "shaker strips". Moreover, the large size and complex nature of such fish shaking equipment precludes usage on smaller fishing vessels and, further, generally requires permanent installation which essentially prevents movement of the shaking equipment to a different operating position on the vessel.